1. Field of the Invention
The present invention relates to an image forming apparatus that is provided with a sheet discharge roller for discharging a sheet material, a sheet discharge tray that is attached to an apparatus main body to be openable and closable thereto and holds the sheet material discharged from the sheet discharge roller, and a recovery unit that is driven in association with the sheet discharge roller.
2. Description of the Related Art
A sheet discharge tray of a typical printing apparatus is configured to be openable and closable around its rotary shaft. This sheet discharge tray is retained in a closed state at the time it is not used, whereby the apparatus can be made to be compact and the entering of dusts and the like into a print unit can be prevented. However, when a print starts in a state where the sheet discharge tray is closed, in some cases there occurs a problem that discharge of the printed sheet material is interrupted by the sheet discharge tray to cause a sheet jam in the apparatus. For overcoming this problem, there is proposed the invention that, when the sheet material is conveyed, the sheet discharge tray is automatically made to be in an open state.
Japanese Patent Laid-Open No. 2010-6608 discloses a printing apparatus comprising a sheet discharge roller for discharging sheet materials, a sheet discharge tray attached to an apparatus main body to be openable and closable thereto for holding the sheet material discharged by the sheet discharge roller, a delay mechanism formed of a plurality of ring members to be rotatable with delay in synchronization with the sheet discharge roller, and a control mechanism formed of a plurality of link members and a plurality of flexible members. Japanese Patent Laid-Open No. 2010-6608 proposes the printing apparatus in which the delay mechanism is provided with a plurality of cam units rotatable with the plurality of the ring members, and a phase control unit for controlling phases of the plurality of the cam units, wherein one link member in the control mechanism is connected to the sheet discharge tray, and when the phases of the plurality of the cam units are in agreement, the sheet discharge tray is opened through the control mechanism by a drive of the sheet discharge roller.
In the delay mechanism of Japanese Patent Laid-Open No. 2010-6608, a predetermined amount of the delay can be accumulated by rotating the sheet discharge roller in a reverse direction to a sheet discharge direction. That is, with the configuration that the sheet discharge roller and a suction pump of a print agent are driven with the same drive source, the pump performs a suction operation in association with the backward rotation of the sheet discharge roller, and a pump initializing operation is performed in association with the forward rotation of the sheet discharge roller, wherein the delay amount is in advance accumulated and the pump is initialized by a drive amount within the delay amount. This can prevent an inadvertent sheet discharge tray opening operation other than at sheet-discharging. The configuration that the sheet discharge tray automatically opens before sheet-discharging is an effective function for preventing a problem such as a sheet jam inside the apparatus. On the other hand, since it is not preferable that the sheet discharge tray inadvertently opens regardless of no schedule of sheet-discharging, such as in a case where a user finishes a print and disconnects a power source of the printing apparatus, it is necessary to perform a delay accumulation operation for preventing the inadvertent sheet discharge tray opening operation.
Recently for the purpose of cost reduction, there is proposed an apparatus configuration that not only the sheet discharge roller and the suction pump, but also a set of a recovery mechanism for performing a recovery operation that makes a state of the print unit good are driven by the same drive source. The recovery operation of the print unit is performed at various timings. The recovery operation is regularly configured of complicated sequence, such as wiping and capping operations, which causes many drive amounts of the recovery mechanism. Therefore in a case of the configuration where the sheet discharge roller rotates in the sheet discharge direction in association with a drive of the recovery mechanism, it is required to perform the delay accumulation operations many times in the middle of the recovery operation for preventing the inadvertent sheet discharge tray opening operation. However, since it takes time to perform the delay accumulation operation, there is a problem that a time (waiting time) for which a user has to wait by the recovery operation is made longer to degrade throughput.